"While I have concerns about reported irregularities in some areas of the district, I'll leave any investigation of those matters to others," Tisei said.

Tierney struggled to contain the fallout from a federal criminal case involving his wife and her family. His wife agreed in October 2010 to plead guilty to federal charges she helped her brothers conceal an illegal offshore gambling operation. She was sentenced to 30 days behind bars.

"In the end it wasn't about our family, and it wasn't about his family. It was about your families," Tierney said.

Tierney said he didn't know the online gambling operation in Antigua was illegal. Tisei accused him of being dishonest with voters.

Tierney is from Salem. He first took office in 1996.

Tisei is a former state senator from Lynnfield. He would have been the first Republican to win a U.S. House race in Massachusetts since 1994.